JPS6062001A - Headlight for vehicle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a headlamp capable of emitting an interception type light beam, which is used as a so-called "European unified beam" type passing headlamp for automobiles or in front of an antique vehicle. It is used to configure lighting.

[Prior art]

It is provided to reduce the size of a uniform-radiating beam headlamp consisting of a structure having the components described below.

Namely, (1) rotation around the axis that defines the optical axis for the reflecting mirror (in the form of an 11-round ellipsoid, the two foci of the spheroid are the first focal point close to the reflector and the second fish point far from it) (2) a light source located near the first focal point of the reflector;
) located on the opposite side of the reflecting mirror with respect to the second focal point of the reflecting mirror and having an optical axis f that coincides with the optical axis of the reflecting mirror;
(4) "Anti-Fog" type or "European Vino," with a converging lens with a focal point located near the focal point;
A shielding plate located near the second focal point of the lens and having an end close to the optical axis to create a shaped blocked beam.

This structure is described, for example, in French Patent No. 8220200 filed by the present applicant on December 2, 1982, entitled "Elliptical mirror cut-off beam headlamp for automobiles", which is cited as a cited document. Are listed.

In order to obtain good photometric efficiency with this type of headlamp, two apertures are required to catch the total luminous flux emitted from the reflector, the effective aperture perpendicular to the optical axis, and the focal length relative to the incident focal length.
It is necessary to use a large lens.

On the other hand, increasing this aperture ratio causes considerable chromatic aberration. These chromatic aberrations are caused by the refractive differences of each threat color, which is a component of the same ray entering the lens, within the incident plane, and the more the ray is refracted, the closer to the periphery of the lens the chromatic aberration becomes. The refracted light rays have large chromatic aberrations.

It is possible to compensate for this aberration in the same way as in photographic optics by replacing the converging lens with a juxtaposed group of lenses that compensate for each chromatic aberration, but this is very complex and expensive.

[Purpose of the invention]

The aim of the invention is to provide a simpler solution particularly adapted to the special circumstances of cut-beam headlamps for motor vehicles.

[Summary of the invention]

Considering that the escape plate in the case of automobile headlights is horizontal or slightly inclined to the horizontal, this chromatic aberration is caused by the lateral region of the lens, F1, which is very inclined to the horizontal. This aberration is not a nuisance if it occurs in a region that does not produce a refraction, but on the contrary, the upper and lower parts of the lens produce spectral phenomena that exhibit unacceptable inaccuracies and coloration for beam blocking W1. show.

To rectify this disadvantage, according to the invention, in order to integrate these spectral phenomena into the residual beam, the upper and lower parts of the vicinity of the lens are provided with lateral dispersion of the light passing through this part of the lens and /or ``This is countered by the provision of local refractive elements that effect the refraction, but these refractive elements may be formed integrally with the lens, preferably in the form of parts cut out on the lens. Alternatively, it may be an integral piece of transparent glass juxtaposed to the lens, or it may be placed on the light source side of the lens to cause dispersion of light rays so as to attenuate aberrations.

According to the test results, the upper and lower end portions of the lens having band-shaped refractive members in contact with the upper and lower edges of the lens, respectively, are limited, and each of these bands is 1/10 of the height of the lens.
It has been shown that a height of between 1/4 and 1/4 results in satisfactory correction of chromatic aberrations when viewed on a screen placed 25 meters from the headlight according to current European regulations.

〔Example〕

Other characteristics and advantages of the invention will become apparent from the following description of non-limiting exemplary embodiments and from the accompanying drawings, which form an integral part of the description.

The conventional structure shown in Fig. 1 for realizing a blocked beam has an optical axis (
2), bifocals (Fl) (close to reflector (1)) and (F2
) (separated) and has an elliptical reflector <1).

A light source (3) (filament) is located near the first focal point (Fl). The light rays emitted from the light source (3) are directed toward the second focal point (F2) by the reflecting mirror (1).

A converging lens (4) is located opposite the reflector (1) with respect to the second focal point (F2), the optical axis of said lens (4) coincides with the optical axis of the reflector, and the focus of said lens Bifocal (F2
) is near. The light rays emitted from the light source (3) are reflected by the reflecting mirror (1
) and converges near the second focal point (F2) and is turned into a useful beam by the lens (4).

Since this beam should be a blocking beam,
More precisely, the shielding screen (5) is the second focal point (F2)
Located near. This screen (5) has an upper end (6) which defines the shielding limit of the beam. In the example shown in FIG. 1, the screen (5) is planar and perpendicular to the optical axis (2), and the shielding end is composed of two half-planes extending from the optical axis. It can be seen that 6 shielding limits (6) are defined on the screen (j) placed at a distance of 25 meters based on the current standard, corresponding to the shielding edge (6).

In this moderate conventional method of the type shown in Figure 1, in order to obtain high photometric efficiency, a relatively large aperture ratio (the ratio of its diameter and focal length It is preferable to use lenses having a ratio of

As a result, chromatic aberrations occur, resulting in coloring of the interruptions on the screen (9). In other words, the edges (6) that constitute the cutoff limit are colored, but this type of chromatic aberration becomes larger the greater the refraction of the light ray, and therefore the closer it is to the periphery of the lens.The dispersion of light occurs, When blue light passes through a lens, it is refracted more than red light.

After carefully observing this phenomenon, we found that this type of chromatic aberration is
It turns out that if this is done for the areas located on the left and right sides of the lens, it is not very difficult because this is the blocking direction, but this means that the minute difference in refraction of each ray that comes to this area is This is because it is ultimately caused by horizontal refraction and is similar to the conventional cutoff limit (for passing beams, the cutoff consists of a horizontal half-plane and a slightly upward half-plane (see (6')). (for anti-fog beams, the cutoff is a horizontal straight line). As a result, the coloring mixes together within the effective luminous flux and hardly appears at the cutoff limit.

On the contrary, for the regions located at the top and bottom of the lens, a dispersion occurs in the vertical direction, which gives rise to a coloration, which rises above the cutoff limit, making it fully visible and definitely improving the clarity of the cutoff. make things worse.

In FIG. 2 we see areas (7) and (8) of the lens at its upper and lower parts, which give rise to a strong coloring of the chromatic aberrations at the cut-off limit (6)'.

To overcome this effect, according to the invention, local refractive elements (9) and 00 are placed in this region to refract and/or laterally disperse the light.

When the light is actually refracted downward, the colored portion tends to be below the cutoff limit.

When using lateral dispersion, or diffusive embossing, the chromatic aberration effect is seen to be greatly reduced at the cut-off level.

The refractive member as described above is one that is integrated with the lens (second a).
(as shown in Figure 2b) or a transparent glass-like object juxtaposed to the lens. In general, a refractive element of this type can be placed at any level of the ray trajectory after the screen (5). In reality, chromatic aberrations occur only at the level of the lens (4), so that the diffusion or dispersion of the light rays on the source side of the lens always attenuates the chromatic aberration effect on the cut-off.

In each particular case, a person skilled in the art can determine without hesitation the nature of the refractive element to be used.

However, it may generally be indicated that the refractive elements are preferably distributed along strips adjoining the upper and lower edges of the lens, respectively, as shown in FIG. 2b. Preferably, the heights of these strips hl) and (h2) are:
1/10 to 1/4 of the height h) of the lens (4) itself
Do it between.

[Brief explanation of the drawing]

Figure 1 is a layout diagram showing the conventional structure of a blocked beam headlamp with an ellipsoidal reflector, a shielding screen and a lens;
Figures a and 2b show side and front views, respectively, of a headlamp lens equipped with a refractive element according to the invention to limit chromatic aberration effects at the level of the cut-off. In the figure, 1 is a reflecting mirror, 2 is an optical axis, 3 is a light source, 4 is a converging lens, 5 is a shielding screen, 6 is its edge, 7 is the upper part of the lens, 8 is the lower part of the lens, 9.10 is local refraction Parts, Fl
is the first focus, F2 is the second focus, h is the lens height, h,
'+h2tit indicates the strip height, respectively.

Claims (4)

[Claims] (1) An elliptical reflector (1) having an optical axis (2), a first focus (Fs) relatively close to the reflector (1), and a second focus (F2) relatively far from the reflector (2). ) and a reflector (1
) a light source (3) located near the first focus (Fl) of the
A second focal point (F2) of the reflective mirror is located on the opposite side of the reflective mirror (1) with respect to the second focal point of the reflective mirror (1) and has an optical axis that coincides with the optical axis (2) of the reflective mirror (1). a converging lens (4) with a focal point near the optical axis (
2) with an edge (6) near the focal point (F
2) with a shielding block IJ-y (5) located near the lens (4) in its upper part (7) and its lower part (
8) a local refracting section t which causes lateral dispersion and/or refraction of the light passing through said upper part (7) and lower part (8) of the lens (4) in order to reduce the effects of chromatic aberration near the blocking part; A headlamp for an automobile, characterized in that it has l'(9,10). (2) A headlamp according to claim 1, characterized in that the refractive members (9, 10) are directly integrated with the lens (4). (3) A headlamp according to claim 1, characterized in that the refractive member (9, 10) is an integral part of a transparent glass-like body juxtaposed to the lens (4). (4) Said upper and lower parts comprising the refractive elements (9, 10) are delimited by strips touching the upper and lower edges of the lens, respectively, the height of each strip bs + bz) being the same as that of the lens (
6. The headlamp according to claim 1, wherein the height of h) is 1710 to 1/4 of h).